渤西沙垒田凸起走滑断裂背景下油气成藏特征

Hydrocarbon accumulation characteristics under the background of strike-slip faults in Shaleitian uplift, west Bohai Sea

以三维高分辨率地震资料为基础,结合实际钻井资料,对沙垒田凸起的断裂特征、沉积体系特征以及成藏模式等进行了深入研究,结果发现,沙垒田凸起发育多组北东向走滑断裂,且呈"雁列式"展布。在剖面上,"雁列式"断层向深部收拢,垂直断距较小,没有明显的水平位移,表现为"花状"构造,同时走滑断裂的位置对应着"沟谷",可改变基底和盖层的高低格局。走滑断裂对凸起区构造圈闭的形成、油气的聚集以及凹陷内古近系扇体的沉积均具有重要控制作用。构造脊是油气长期聚集的有利区带,受走滑断裂活动强度差异的影响,沙垒田凸起东段和西段油气的运聚模式存在一定差异:在东段,走滑作用相对较弱,圈闭在走滑断裂之间发育,属于"构造脊-断层-砂体"油气运移模式;在西段,走滑作用强,圈闭依附于走滑断裂发育,属于"沟谷充填砂-走滑断裂系"油气侧向运移模式。

Based on 3D high resolution seismic data, combined with actual drilling data, the fault characteristics, depositional system characteristics and hydrocarbon accumulation model in Shaleitian uplift were studied. The result indicates that multiple sets of NE striking-slip faults are developed in the study area, which gradually converge to the main strikeslip faults to the deep, and the vertical fault throw is smaller without obvious horizontal displacement showing negative flower structure on profile. Meanwhile, the location of the strike-slip faults corresponds to ＂groove＂, which controls the structural framework of the basement and caprock. The NE trending striking-slip faults plays important controlling roles on the formation of structural trap, the deposition of fan bodies and hydrocarbon accumulation. Structure ridge is a favorable zone for oil and gas accumulation. Affected by strike-slip motion, the main hydrocarbon migration and accumulation model in the east is different from the west. In the east, the slipping is relatively weak, and the hydrocarbon migration type is ＂structural ridge-fault-sand body＂ model with traps developing between strike-slip faults. In the west,the slipping is relatively strong, and the lateral hydrocarbon migration type is ＂gully filling sand-strike slip fault system＂model with traps developing attach to the strike-slip faults.